Suryakanta Which One Is Better For Concrete-Rounded or Angular Aggregate Angular aggregate are superior to rounded aggregate from the following two points of view. Angular aggregate exhibit a better interlocking effect in concrete, which property makes it superior in concrete used for roads and pavements. The total surface area of rough textured angular aggregate is more … Read more
Objective To measure flow value of concrete using flow table apparatus Equipment Flow table Slump cone shaped mould Wooden tamping bar Procedure Place the flow table on a leveled surface Clean the top of the table and inner surface of the mould using a damp cloth. Place the slump cone centrally on the table. … Read more
Angularity Number Angularity number is used to give an indication of shape of aggregate. The concept of angularity number was suggested by Shergold. It gives a qualitative representation of shape of aggregate. Angularity Number Test Angularity number test gives an idea of how angular the aggregate is. This is based on the percentage of voids … Read more
Important Notes on Setting Time Test of Cement o It is essential that cement set neither too rapidly nor too slowly. In the first case there might be insufficient time to transport and place the concrete before it becomes too rigid. In the second case too long a setting period tends to slow up the … Read more
Test Standard Reference IS:4031(Part 4):1988-Methods of physical tests for hydraulic cement (Determination of consistency of standard cement paste) Overview Standard consistency of a cement paste is defined as that consistency which will permit a vicat plunger having 10 mm dia and 50 mm length to penetrate to a depth of 33-35 mm from top of … Read more
Prevention to Damage Freshly laid concrete is liable to damage due to heavy impacts. In order to prevent damage: Floors should be covered in order to avoid surface damage Projecting ornamental members should be protected against falling material. Projecting reinforcing bars should not be used for climbing or subjected to severe usage. Stripping of forms … Read more
In normal circumstances (generally where temperature are above 200C), and where ordinary cement is use, forms may be struck after expiry of following periods: Walls, columns and vertical sides of beams 24 to 48 hours as may be decided by the engineer in charge Slabs (props left under) 3 days Beam soffits (props left under) … Read more
Advantages of Precast Concrete Following are the advantages of precast concrete: The concrete of superior quality is produced as it is possible to have better technical control on the production of concrete in factory. It is not necessary to provide joints in the precast construction. The labour required in the manufacturing process of the precast … Read more
Effects of Improper Curing Following are the major disadvantages of improper curing of concrete: The chances of ingress of chlorides and atmospheric chemicals are very high The compressive strength and flexural strengths are lowered. The cracks are formed due to plastic shrinkage, drying shrinkage and thermal effects. The durability decreases due to higher permeability. The … Read more
Properties of Cement Concrete The cement concrete possesses the following important properties: It possesses a high compressive strength. It is a corrosion resistance material and atmospheric agent has no appreciable effect on it. It hardens with age the process of hardening continues for a long time after the concrete has attained sufficient strength. It is … Read more